==Communication==
In Diep.io, many communicate with their name, with names such as: “Spin to Team”, “Kill BLANK”, or even “Pls no kill, me noob”. But names aren’t the only way to communicate. Body language is the main way to communicate in Diep.io, which is believed to have stemmed from the name: “Spin to Team”.
==Spinning==
Spinning is when a tank moves its gun around in a circular motion (smashers which don’t have guns move in a circular motion to ‘spin’), usually the tank doesn’t move or shoot when it spins. Spinning has some implications: the player is online (as sometimes people have to leave their computer, and their tank is left unattended), they are not farming (shooting different polygon shapes to level up), they aren’t trying to travel, and they aren’t trying to kill anyone. This means that spinning has no use to leveling up, the only possible use of spinning is for talking. Like all languages, context is a huge factor in understanding what others are saying. Since the name: “Spin to Team” has been used so many times it is a given that when someone spins they are trying to team with you. However that is not always the case, let’s say a tank is attacking another, and there is no hope for the smaller tank to either fight or run. The smaller tank may spin to plead with the bigger tank to spare its life. Or, let's say a tank starts inching towards a smaller tank and the bigger tank spins. Usually that is an indicator that the tank is trying to trick the smaller tank to lower it’s guard in order to kill it. Sometimes, the bigger tank is being kind, and it’s your choice whether to trust them or not. Also, spinning is sometimes a congratulatory spin, or something you do when you’re happy. Practically it can be a sign of victory, as it may even be used when you successfully communicate in giving someone you are teamed with to take a pentagon (as pentagons are one of the rarer shapes, thus giving more points). Also, many spin after they and their team win in Domination. Generally, spinning is a positive message; like teaming, congratulating, spurring someone on, an affirmative, ect.
==Pointing and More==
Your gun points towards your mouse. Thus, where a tank’s gun is pointing to is where its attention is fixed. However, where a tank’s gun is pointed might be the direct opposite of where its attention is fixed, because if the tank is shooting out bullets while moving in the opposite direction it is ‘boosting itself’. Since there is some recoil from shooting bullets, ‘boosting’ is the fastest way to move around. Fighters and Boosters however have most of their guns on their back side, with one gun in front which points at the mouse. These guys whether boosting or not, their attention should be fixed on where their front gun is generally pointing to.
Now, with the fact in mind that a tank’s gun points to where its attention is fixed, a tank’s gun gives the illusion of being the head/face of the tank. Just like real heads, the front gun of a tank can nod a no, point at stuff, and give a caring head shake at someone.
Tanks can’t nod a yes like us, but they have spinning to take its place. So how do tanks nod a no? When tanks nod a no, they kind of move their gun 30 degrees to one side, and then 60 degrees back the other way, and then 60 degrees back the way they came: repeating the cycle in the same kind of frequency as we say no with our heads. Also, tanks can nod no when they shake their gun around erratically and fast.
To point with their gun, it is fairly easy. Just like a finger, it points at one thing (the gun stays a bit so others can see its pointing at something), then it can point at another thing. Here’s an example on what pointing can be used to do: two tanks on the same team are farming, both tanks spot a pentagon, and one tank points at the pentagon then points at his teammate. The tank starts repeating the process until the other tank realizes that the pointing tank wants him to take the pentagon.
Caring head shakes are a bit hard to explain. Just like language, it needs context. The caring head shake won’t seem caring right after you stole someone’s polygon. The caring head shake doesn’t have the gun move around as much as nodding no. The caring head shake does move its gun back and forth over like nodding no though. I think it best compared to people who do little waves with their hands to say hi or bye.